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INTRODUCTION: Research assuming linearity has concluded that corneal biomechanics are compromised in high myopia. We investigated whether this assumption was appropriate and re-examined these associations across different levels of myopia. METHODS: Myopic (spherical equivalent refraction, SER ≤ -0.50 D) eyes of 10,488 adults aged 40-69 years without any history of systemic and ocular conditions were identified in the UK Biobank. Ordinary least squares (OLS) regression was employed to test the linear association between corneal hysteresis (CH) or corneal resistance factor (CRF), separately, and SER while controlling for age, sex, corneal radius and intraocular pressure. Quantile regression (QR) was used to test the same set of associations across 49 equally spaced conditional quantiles of SER. RESULTS: In OLS regression, each standard deviation (SD) decrease in CH and CRF was associated with 0.08 D (95% CI: 0.04-0.12; p < 0.001) and 0.10 D (95% CI: 0.04-0.15; p < 0.001) higher myopia, respectively. However, residual analysis indicated that the linearity assumption was violated. QR revealed no evidence of a significant association between CH/CRF and SER in low myopia, but a significant (p < 0.05) positive association became evident from -2.78 D (0.06 and 0.08 D higher myopia per SD decrease in CH and CRF). The magnitude of association increased exponentially with increasing myopia: in the -5.03 D quantile, every SD decrease in CH and CRF was associated with 0.17 D (95% CI: 0.08-0.25; p < 0.001) and 0.21 D (95% CI: 0.10-0.31; p < 0.001) higher myopia. In the -8.63 D quantile, this further increased to 0.54 D (95% CI: 0.33-0.76; p < 0.001) and 0.67 D (95% CI: 0.41-0.93; p < 0.001) higher myopia per SD decrease in CH and CRF. CONCLUSIONS: Corneal biomechanics appeared compromised from around -3.00 D. These changes were observed to be exponential with increasing myopia.
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Córnea , Pressão Intraocular , Refração Ocular , Humanos , Pessoa de Meia-Idade , Córnea/fisiopatologia , Feminino , Masculino , Adulto , Idoso , Fenômenos Biomecânicos , Refração Ocular/fisiologia , Pressão Intraocular/fisiologia , Miopia/fisiopatologia , Miopia/epidemiologia , Elasticidade , Miopia Degenerativa/fisiopatologiaRESUMO
PURPOSE: To evaluate the changes in corneal biomechanical properties and tear film layer analysis after upper eyelid blepharoplasty surgery. METHOD: Sixty eyes of 30 patients were included in our prospective study. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated intraocular pressure (IOPcc) and Goldmann intraocular pressure (IOPg) measurements were taken with the Ocular Response Analyzer (ORA) device at the preoperative, postoperative 1st and 3rd months. The ocular surface was evaluated with tear breakup time (TBUT) and Ocular Surface Disease Index (OSDI) scores. Lid crease (LC), margin-to-reflex distance 1 (MRD1), and palpebral fissure height (PFH) were evaluated at each visit. RESULTS: In the ORA analysis, in the 1st month CH value was found to be significantly lower than the preoperative value (preoperative 13.39 ± 6.08 mmHg; 1st month 10.74 ± 1.94 mmHg, p = 0.011). In addition, there was a statistically significant decrease in the 3rd month value compared to the preoperative values (10.46 ± 1.69 mmHg, p = 0.021). However CRF decreased postoperatively, no statistical difference was detected (preop 12.59 ± 3.84; 1st month 11.94 ± 3.04; 3rd month 9.78 ± 1.74; p = 0.149). While there was a decrease in IOPcc and IOPg in the postoperative period, no statistical difference was detected (respectively p = 0.96, p = 0.71). In the postoperative 1st month, TBUT increased significantly (p = 0.024). When those with a TBUT value below 10 were considered dry eye, significant decrease was observed in the percentage of dry eye in the first postoperative month (p = 0.027). Although the dry eye percentage decreased in the 3rd month compared to the preoperative percentage, no statistical difference was detected (p = 0.125). There was a significant decrease in the number of those with an OSDI score above 13 in the first month (p = 0.004). CONCLUSION: In our study, a decrease in ORA values was observed after blepharoplasty, with only CH being statistically significant. Reducing the load on the cornea after surgery may change the corneal biomechanics. These changes should be taken into consideration after eyelid surgery, especially in patients who may require glaucoma follow-ups.
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Blefaroplastia , Córnea , Pálpebras , Pressão Intraocular , Lágrimas , Humanos , Blefaroplastia/métodos , Feminino , Córnea/cirurgia , Córnea/fisiopatologia , Masculino , Estudos Prospectivos , Pessoa de Meia-Idade , Pressão Intraocular/fisiologia , Pálpebras/cirurgia , Pálpebras/fisiologia , Fenômenos Biomecânicos , Lágrimas/fisiologia , Lágrimas/metabolismo , Adulto , Idoso , Seguimentos , Período Pós-Operatório , Elasticidade/fisiologiaRESUMO
INTRODUCTION: Corneal biomechanical properties could affect intraocular pressure (IOP) measurement. The aim of this study was to evaluate the differences in corneal biomechanical properties of various types of glaucoma, assess their effect on IOP measurements. METHODS: This is an observational clinical study of 486 subjects including 102 normal subjects, 104 ocular hypertension (OHT), 89 normal tension glaucoma (NTG), and 191 high tension glaucoma (HTG). Corneal biomechanical parameters were measured using an ocular response analyzer. The main parameters assessed were corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated pressure measurement (IOPg), and corneal-compensated intraocular pressure (IOPcc). Ultrasound pachymetry was used to measure central corneal thickness (CCT). IOP was measured by a Goldmann applanation tonometer (GAT) and a noncontact tonometer (NCT). Visual field (VF) and refractive status were also recorded. Results were analyzed by one-way analysis of variance, univariate and multivariate linear regression analyses, and Bland-Altman plots. RESULTS: Multiple comparison by analysis of variance showed significantly lower CH and CRF in NTG compared to HTG, OHT, and normal subjects (CH: 0.011, 0.015, and 0.033; CRF: 0.001, <0.001, and 0.042, respectively). CRF and CH associated with IOP were measured using either GAT, NCT and IOPcc-GAT, IOPcc-NCT, yet CCT was not. GAT correlated strongly with IOPg (r = 0.79; p < 0.001) and IOPcc (r = 0.77; p < 0.001), but limits of agreement between the measurements were poor. CH and CRF were both negatively correlated with VF change (p < 0.01). CONCLUSION: CH and CRF affect the measurement of IOP and were related to types of glaucoma or severity of glaucoma. Pure CCT should not be used to correct IOP values or estimate the risk of disease.
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Glaucoma , Glaucoma de Baixa Tensão , Hipertensão Ocular , Humanos , Pressão Intraocular , Tonometria Ocular , Glaucoma/diagnóstico , Córnea/fisiologia , Hipertensão Ocular/diagnóstico , Glaucoma de Baixa Tensão/diagnóstico , Fenômenos BiomecânicosRESUMO
Background and Objectives: Hyperopia is a refractive error which affects cognitive and social development if uncorrected and raises the risk of primary angle-closure glaucoma (PACG). Materials and Methods: The study included only the right eye-40 hyperopic eyes in the study group (spherical equivalent (SE) under pharmacological cycloplegia over 0.50 D), 34 emmetropic eyes in the control group (SE between -0.50 D and +0.50 D). A complete ophthalmological evaluation was performed, including autorefractometry to measure SE, and additionally we performed Ocular Response Analyser: Corneal Hysteresis (CH), Corneal Resistance Factor (CRF); specular microscopy: Endothelial cell density (CD), Cell variability (CV), Hexagonality (Hex), Aladdin biometry: Anterior Chamber Depth (ACD), Axial Length (AL), Central Corneal Thickness (CCT). IBM SPSS 26 was used for statistical analysis. Results: The mean age of the entire cohort was 22.93 years (SD ± 12.069), 66.22% being female and 33.78% male. The hyperopic eyes had significantly lower AL, ACD, higher SE, CH, CRF. In the hyperopia group, there are significant, negative correlations between CH and AL (r -0.335), CRF and AL (r -0.334), SE-AL (r -0.593), ACD and CV (r -0.528), CV and CRF (r -0.438), CH (r -0.379), and positive correlations between CCT and CH (r 0.393) or CRF (r 0.435), CD and ACD (r 0.509) or CH (0.384). Age is significantly, negatively correlated with ACD (r -0.447), CH (r -0.544), CRF (r -0.539), CD (r -0.546) and positively with CV (r 0.470). Conclusions: Our study suggests a particular biomechanical behavior of the cornea in hyperopia, in relation with morphological and endothelial parameters. Moreover, the negative correlation between age and ACD suggests a shallower anterior chamber as patients age, increasing the risk for PACG.
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Hiperopia , Erros de Refração , Humanos , Feminino , Masculino , Adulto Jovem , Adulto , Hiperopia/complicações , Face , Córnea , BiometriaRESUMO
PURPOSE: To evaluate the corneal biomechanical properties and central corneal thickness in patients with Graves' orbitopathy (GO). METHOD: A total of 132 eyes of 66 patients with GO and 108 eyes of 54 healthy subjects were enrolled. Eyes with GO were classified as high score clinical activity score (CAS, ≥ 3) (Group 1, n = 64) and low CAS score (< 3) (Group 2, n = 68). Corneal biomechanical parameters [corneal hysteresis (CH), corneal resistance factor (CRF)], Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) levels were measured with Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, Buffalo, NY) and compared between the groups. RESULTS: The mean CH values were found as 9.6 ± 1 mmHg in Group 1, 10.2 ± 0.9 mmHg in Group 2, and 11.4 ± 1.7 mmHg in the Control Group (p < 0.001). In post hoc analysis the mean CH was significantly lower in Group 1 than Group 2 and Control Group (Group 1-Group 2, p < 0.001; Group 1-Control Group, p < 0.001). The mean CRF was found as 10.5 ± 2.1 in Group 1, 10.4 ± 2.2 in Group 2, and 10.43 ± 2.0 in the Control group. There was no statistically significant difference between the groups in CRF measurements (p = 0.959). The mean IOPcc values were found as 17.1 ± 3.6 mmHg in Group 1, 15.8 ± 4.0 mmHg in Group 2 and 15.2 ± 4.1 mmHg in the Control Group. The IOPcc and IOPg measurements between all groups were statistically significant (p = 0.009, p = 0.027, respectively). CONCLUSIONS: Corneal biomechanical measurements were different in the GO patients with varying CAS scores compared to healthy individuals.
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Oftalmopatia de Graves , Humanos , Oftalmopatia de Graves/diagnóstico , Córnea/fisiologia , Pressão Intraocular , Tonometria Ocular , Voluntários Saudáveis , Fenômenos Biomecânicos/fisiologia , ElasticidadeRESUMO
PURPOSE: To evaluate corneal biomechanical changes after Descemet stripping automated endothelial keratoplasty (DSAEK), penetrating keratoplasty (PK), and phacoemulsification (PE). METHODS: This prospective study included 138 eyes which underwent PK (26 eyes), DSAEK (26 eyes), PE (57 eyes), and 29 normal eyes. Intraocular pressure (IOP) was measured by Goldmann applanation tonometer (GAT), and central corneal thickness (CCT) and axial length by ultrasound. The ocular response analyzer was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-related IOP (IOPg), and cornea-compensated IOP (IOPcc) preoperatively and 1, 3, and 6 months postoperatively. RESULTS: At baseline, PK group had the lowest CH and CRF. There was a significant increase in CH and CRF to normal values in PK (P = 0.015 and 0.006) and PE (P = 0.005 and 0.0001) groups over the study period. At 6 months, CH and CRF increased and reached normal values in the PK group; increased to a lower level than normal in the DSAEK group; and, after an initial reduction, increased to normal values in the PE group. At 6 months, DSAEK group had the lowest CH and CRF. There was a significant positive correlation between CRF and GAT (r = 0.281, P = 0.009), IOPg and GAT (r = 0.335, P = 0.001), and IOPcc and GAT (r = 0.282, P = 0.001). CH was negatively correlated with age (r = - 0.189, P = 0.04). CONCLUSION: Corneal biomechanical factors increase after DSAEK and PK. At post-operative month six, they reach normal values in PK group, but are lower than normal in DSAEK group.
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Ceratoplastia Endotelial com Remoção da Lâmina Limitante Posterior , Facoemulsificação , Fenômenos Biomecânicos , Córnea/fisiologia , Córnea/cirurgia , Humanos , Pressão Intraocular , Ceratoplastia Penetrante , Estudos Prospectivos , Tonometria OcularRESUMO
PURPOSE: To investigate the effect of "skin-only" upper eyelid blepharoplasty on corneal biomechanics and central as well as peripheral topographic/tomographic parameters before and 4 weeks after surgery. METHODS: In a prospective study, the corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated before and after blepharoplasty. Corneal topographic (maximum simulated keratometry value, inferior-superior value, index of surface variance, index of vertical asymmetry, index of height asymmetry, index of height decentration) and tomographic parameters (corneal thickness, corneal astigmatism and mean 5-mm- and 7-mm-zone keratometry value) were measured by the Pentacam HR. Statistical analysis was performed using a linear mixed model considering correlated data of both eyes. RESULTS: This study included 42 eyes of 35 patients (mean age: 64.5 years, range 52-82 years). Four weeks after surgery CH and CRF increased (9.4 ± 2.3 to 10.2 ± 2.2 mmHg and 9.7 ± 2.1 to 10.5 ± 2.2 mmHg) but did not reach statistical significance (P = 0.100 and P = 0.072). A significant increase in central maximum simulated keratometry value (Kmax) from 45.0 ± 2.3 to 45.4 ± 2.2 diopters (D) was observed (P = 0.004). Inferior-superior value (I-S) and index of surface variance (ISV) showed significant changes from 0.32 ± 0.98 to 0.10 ± 0.98 D (P = 0.02) and from 19.98 ± 9.84 to 22.93 ± 11.23 (P = 0.009), respectively. These alterations did not affect the subjective spherical equivalent (-0.09 ± 4.71 to -0.04 ± 4.51 D; P = 0.437) and the best-corrected distance visual acuity of patients (0.11 ± 0.14 to 0.15 ± 0.15 logMAR; P = 0.142). Age, gender and corneal thickness were not correlated with pre and postoperative differences of CH, CRF, corneal compensated IOP, Kmax, corneal astigmatism or I-S. CONCLUSION: The trend of increasing CH and CRF values might indicate a rise of corneal damping capacity. Despite statistically significant differences of Kmax, I-S and ISV, all other tomographical and topographical parameters did not change 4 weeks after surgery. The corneal steepening with a mean change of 0.4 diopters and the decrease of I-S with a mean of 0.22 diopters do not seem to have a clinically relevant effect for blepharoplasty patients in daily practice.
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Blefaroplastia , Idoso , Idoso de 80 Anos ou mais , Fenômenos Biomecânicos , Córnea/diagnóstico por imagem , Córnea/cirurgia , Topografia da Córnea , Pálpebras , Humanos , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
Background and Objectives: There is a clear evidence that pregnancy is associated with high production of sex hormones. During the first, second and third trimester of pregnancy, blood hormones levels increase gradually. Cells with affinity for sex hormones have been identified in different ocular tissues, such as: lid, lacrimal gland, meibomian gland, bulbar and palpebral conjunctivae, cornea, iris, ciliary body, lens, retina (retinal pigment epithelium) and choroid. This is why pregnancy is associated with changes at ocular level, involving anterior and posterior segments. Several clinical trials have been made trying to highlight changes in corneal biomechanics during pregnancy. By conducting this review, we want to evaluate both the changes in parameters that define corneal biomechanics and intraocular pressure values in pregnant. Materials and Methods: Following a systematic search in the literature related mainly to changes in corneal biomechanics during pregnancy, focusing on the paper published in the last decade, we included in a meta-analysis the cumulative results of three prospective comparative studies. Results: Important changes in corneal biomechanics (corneal hysteresis and corneal resistance factor) parameters were observed in women in the third trimester of pregnancy, but these variations were not statistically significant. Also, a decrease in intraocular pressure was mentioned in these women, but only the corneal compensation intraocular pressure showed a decrease with statistical significance. Conclusions: A decrease in corneal compensatory intraocular pressure was observed in pregnant women in the third trimester of pregnancy, but without other statistically significant changes resulting from the analysis of the other three parameters (corneal hysteresis, corneal resistance factor and Goldmann-correlated intraocular pressure).
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Córnea , Tonometria Ocular , Fenômenos Biomecânicos , Feminino , Humanos , Pressão Intraocular , Gravidez , Terceiro Trimestre da Gravidez , Estudos ProspectivosRESUMO
BACKGROUND: To evaluate corneal biomechanical properties by the Ocular Response Analyzer (ORA) in non keratoconic patients underwent penetrating keratoplasty (PK). METHODS: Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann- correlated intraocular pressure (IOPg), cornea-compensated IOP (IOPcc) using the ORA, and central graft thickness (CGT) were measured in 30 eyes at least two years after penetrating keratoplasty for non keratoconic indications. IOP using the Goldmann applanation tonometer (GAT) was also obtained after compensation for graft thickness and astigmatism. RESULTS: The mean age of patients was 33.1 ± 10.13 years; indications for PK were herpetic corneal scar (53.3%), corneal stromal dystrophy (23.3%), traumatic corneal opacity (10%), chemical corneal opacity (6.7%), and Fuchs endothelial dystrophy (6.7%). Mean CH and CRF were 8.52 ± 1.81 mmHg, and 8.56 ± 1.59 mmHg, respectively. Mean CGT was 532.43 ± 30 µm. Mean IOP GAT, IOPg, and IOPcc were 11.88 ± 3.66, 14.64 ± 4.08, and 17.27 ± 4.60 mmHg, respectively (P < 0.001). No significant association was found between CGT and IOP readings obtained using either the ORA or GAT. There were significant negative association between CH with both IOP GAT and IOPcc, while CRF had significant positive association with IOPg. CONCLUSION: After penetrating keratoplasty for non keratoconic patients, graft biomechanics does not return to average values even 2 years after the operation; moreover, intraocular pressure measurement with ORA gives higher values than thickness compensated GAT.
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Córnea/fisiopatologia , Opacidade da Córnea/cirurgia , Distrofia Endotelial de Fuchs/cirurgia , Pressão Intraocular/fisiologia , Ceratoplastia Penetrante/métodos , Adulto , Idoso , Córnea/cirurgia , Opacidade da Córnea/fisiopatologia , Estudos Transversais , Elasticidade , Feminino , Seguimentos , Distrofia Endotelial de Fuchs/fisiopatologia , Humanos , Ceratocone , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Tempo , Tonometria Ocular/métodos , Acuidade Visual , Adulto JovemRESUMO
BACKGROUND: Compare Goldmann applanation tonometer (GAT) prism and correcting applanation tonometry surface (CATS) prism to intracameral intraocular pressure (IOP), in vivo and in vitro. METHODS: Pressure transducer intracameral IOP was measured on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically to 10, 20, and 40 mmHg. Simultaneously, IOP was measured using a Perkins tonometer with a standard GAT prism and a CATS prism at each of the intracameral pressures. Statistical comparison was made between true intracameral pressures and the two prism measurements. Differences between the two prism measurements were correlated to central corneal thickness (CCT) and corneal resistance factor (CRF). Human cadaver eyes were used to assess measurement repeatability. RESULTS: The CATS tonometer prism measured closer to true intracameral IOP than the GAT prism by 1.7+/-2.7 mmHg across all pressures and corneal properties. The difference in CATS and GAT measurements was greater in thin CCT corneas (2.7+/-1.9 mmHg) and low resistance (CRF) corneas (2.8+/-2.1 mmHg). The difference in prisms was negligible at high CCT and CRF values. No difference was seen in measurement repeatability between the two prisms. CONCLUSION: A CATS prism in Goldmann tonometer armatures significantly improve the accuracy of IOP measurement compared to true intracameral pressure across a physiologic range of IOP values. The CATS prism is significantly more accurate compared to the GAT prism in thin and less rigid corneas. The in vivo intracameral study validates mathematical models and clinical findings in IOP measurement between the GAT and CATS prisms.
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Erros de Diagnóstico , Pressão Intraocular/fisiologia , Modelos Teóricos , Hipertensão Ocular/diagnóstico , Tonometria Ocular/instrumentação , Idoso , Cadáver , Desenho de Equipamento , Feminino , Humanos , Masculino , Hipertensão Ocular/fisiopatologia , Estudos Prospectivos , Reprodutibilidade dos TestesRESUMO
PURPOSE: To investigate the effects of dehydration and fasting on the intraocular pressure (IOP) and corneal biomechanics during Ramadan in healthy subjects. METHODS: A total of 36 healthy fasting male volunteers with a mean age of 32.7 ± 5.1 years (range 28-38 years) were enrolled in the study. A Reichert Ocular Response Analyzer (ORA) was used to measure the corneal resistance factor (CRF), corneal hysteresis (CH), Goldman-correlated IOP (IOPg), and corneal-compensated IOP (IOPcc), additionally IOP with Goldmann applanation tonometer (IOP-GAT) was taken. All measurements were recorded at 8:00 am and 4:00 p.m. during Ramadan and during a 1-month follow-up after Ramadan was over. RESULTS: Statistical analysis demonstrated no difference in the ORA measurements including CH, CRF, IOPcc, and IOPg; CCT and CV values between fasting and non-fasting periods or within a single day (diurnal changes). Nine volunteers (25% of total subjects) were excluded because eyedrops were believed to disrupt the Ramadan fast consequently IOP-GAT could not be measured from these subjects. No statistically significant difference was noted between IOP-GAT and IOPg measurements of twenty-seven subjects at the different periods and time points. CONCLUSIONS: Our results reveal that fasting during Ramadan does not profoundly affect corneal biomechanics and IOP values in healthy volunteers without ocular diseases such as glaucoma. When planning corneal refractive surgery and determining IOP, the ORA measurements can be done safely during a Ramadan fast. Moreover, ORA may be a better alternative for patients that refuse IOP measurement via GAT for examining the accuracy of IOP during fasting. Further studies are needed to better understand the role of these parameters on corneal disease and glaucoma during fasting.
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Córnea/fisiologia , Desidratação/fisiopatologia , Jejum/fisiologia , Pressão Intraocular/fisiologia , Adulto , Idoso , Fenômenos Biomecânicos , Humanos , Masculino , Pessoa de Meia-Idade , Tonometria OcularRESUMO
PURPOSE: Corneal hysteresis (CH) and corneal resistance factor (CRF) are corneal biomechanical parameters which were measured by ocular response analyzer (ORA). Aim of this study was to define the CH and CRF in high myopic and hyperopic patients and compare the results with emmetropic control group. METHODS: A total of 193 eyes of 100 healthy volunteers were included. Study groups were high myopic patients (n = 27) with spherical refractive errors (SRE) of greater than -5.00D, high hyperopic patients (n = 20) with SRE of greater than +3.00D and controls (n = 53) with SRE between ± 1.00D. All subjects underwent IOP and corneal biomechanical evaluation with the ORA. Also Goldmann applanation tonometry (GAT), central corneal thickness (CCT), corneal curvature and axial length measurements were taken. RESULTS: Mean age of groups was 30.7 ± 6.9, 29.1 ± 7.7, 28.9 ± 5.6 years (p > 0.05). Among study groups except CRF and CCT, all parameters were significantly different between study groups. CH was lowest in the high myopic group and highest in the high hyperopia. In all groups, there were significant correlations between CH and CRF, CCT, SRE, SE (spherical equivalent), AL (axial length) and between CRF and CCT. GAT and IOPg (Goldmann-correlated intraocular pressure) measurements were significantly correlated with CCT (p < 0.05). One of the major findings was as the CH approaches 11.2 mmHg, IOPcc (corneal-compensated intraocular pressure) and IOPg get close to each other. CONCLUSIONS: The results revealed that CRF is not affected by refractive errors and IOPcc is not affected by any other ocular parameter. The difference between IOPcc and IOPg was greatest in myopic group, and IOP (intraocular pressure) measurement in these patients deserves high suspicion.
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Córnea/fisiopatologia , Pressão Intraocular/fisiologia , Refração Ocular/fisiologia , Erros de Refração/fisiopatologia , Adulto , Elasticidade , Feminino , Humanos , Masculino , Erros de Refração/diagnóstico , Índice de Gravidade de Doença , Tonometria Ocular/métodos , Adulto JovemRESUMO
In this prospective study, the biomechanical properties of optic nerve head (ONH) and cornea in both eyes of patients with non-arteritic anterior ischaemic optic neuropathy and healthy control eyes were investigated. ONH elastometry was measured with real-time elastography, and corneal elastometry was measured with ocular response analyser. Elastometry of cornea and ONH was lower in both eyes of patients with unilateral non-arteritic ischaemic optic neuropathy than in healthy control eyes. The role of these biomechanical differences in the pathogenesis of non-arteritic ischaemic optic neuropathy should be investigated further.
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BACKGROUND: To compare corneal hysteresis (CH) measurements between patients with glaucoma, ocular hypertension (OHT) and glaucoma-like optic discs (GLD)- defined as a cup to disc ratio greater than or equal to 0.6 with normal intraocular pressure (IOP) and visual fields. The secondary aim was to investigate whether corneal resistance factor (CRF) and central corneal thickness (CCT) differ between patient groups. METHODS: In this cross sectional study a total of 123 patients (one eye each) were recruited from a glaucoma outpatient department to undergo ocular response analyser (ORA) testing and ultrasound pachymetry as well as clinical examination. A One-way Analysis of Covariance (ANCOVA) was conducted to evaluate the mean difference in CH between the three diagnostic groups (glaucoma, OHT and GLD) correcting for potential confounding factors, IOP and age. Analysis was repeated for CRF and CCT. RESULTS: There was a significant difference in mean CH across the three diagnosis groups; F(2, 115) = 96.95; p < 0.001. Mean CH significantly higher for GLD compared to glaucoma (mean difference 1.83, p < 0.001), and significantly higher for OHT compared to glaucoma (mean difference 2.35, p < 0.001). Mean CH was slightly lower in patients with GLD than those with OHT but this difference was not statistically significant. A similar pattern was seen when the analysis was repeated for CRF and CCT. CONCLUSIONS: Higher CH in GLD and OHT compared to glaucoma suggests increased viscoelasticity of ocular tissues may have a protective role against glaucoma.
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Córnea/fisiopatologia , Elasticidade/fisiologia , Glaucoma/fisiopatologia , Hipertensão Ocular/fisiopatologia , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Fenômenos Biomecânicos , Córnea/patologia , Estudos Transversais , Feminino , Glaucoma/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Hipertensão Ocular/patologiaRESUMO
BACKGROUND: Goldmann applanation tonometry (GAT) error relative to intracameral intraocular pressure (IOP) has not been examined comparatively in both human cadaver eyes and in live human eyes. Futhermore, correlations to biomechanical corneal properties and positional changes have not been examined directly to intracameral IOP and GAT IOP. METHODS: Intracameral IOP was measured via pressure transducer on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically on each patient alternately to 10, 20, and 40 mmHg. IOP was measured using a Perkins tonometer in the supine position on 58 eyes and upright on a subset of 8 eyes. Twenty one (21) fresh human cadaver globes were Intracamerally IOP adjusted and measured via pressure transducer. Intracameral IOP ranged between 5 and 60 mmHg. IOP was measured in the upright position with a Goldmann Applanation Tonometer (GAT) and supine position with a Perkins tonometer. Central corneal thickness (CCT) was also measured. RESULTS: The Goldmann-type tonometer error measured on live human eyes was 5.2 +/-1.6 mmHg lower than intracameral IOP in the upright position and 7.9 +/- 2.3 mmHg lower in the supine position (p < .05). CCT also indicated a sloped correlation to error (correlation coeff. = 0.18). Cadaver eye IOP measurements were 3.1+/-2.5 mmHg lower than intracameral IOP in the upright position and 5.4+/- 3.1 mmHg in the supine position (p < .05). CONCLUSION: Goldmann IOP measures significantly lower than true intracameral IOP by approximately 3 mmHg in vitro and 5 mmHg in vivo. The Goldmann IOP error is increased an additional 2.8 mmHg lower in the supine position. CCT appears to significantly affect the error by up to 4 mmHg over the sample size.
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Córnea/fisiologia , Pressão Intraocular/fisiologia , Hipertensão Ocular/diagnóstico , Tonometria Ocular/métodos , Fenômenos Biomecânicos , Cadáver , Humanos , Sensibilidade e Especificidade , Tonometria Ocular/normasRESUMO
PURPOSE: The aim of this study was to evaluate the corneal biomechanical parameters in patients with ankylosing spondylitis (AS) and to compare them with the healthy subjects. METHODS: Sixty patients with AS (study group) and 60 healthy subjects (control group) were enrolled in this prospective study. The study group was further classified as active (n:30) and inactive (n:30). After detailed ophthalmological examination including intraocular pressure (IOP) measurement with Goldmann applanation tonometer (IOPGAT), corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) were measured with the Reichert Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was measured with the Spectral-Domain Optical Coherence Tomography (SD-OCT). RESULTS: The study group's mean CH, CCT, IOPg, and IOPGAT values were lower than the control group (p < 0.05 for all variables). The mean CH, CRF, CCT, IOPg, and IOPGAT values were higher in active patients when compared to the inactive ones (p < 0.001, p < 0.001, p = 0.013, p = 0.021, and p = 0.002, respectively). CONCLUSIONS: AS patients have lower CCT, CH, IOPg, and IOPGAT when compared with healthy subjects. In the active stage of AS, patients present with higher levels of corneal biomechanical parameters with thicker corneas. IOPcc is a more accurate measurement than IOPGAT or IOPg in AS patients.
Assuntos
Córnea/fisiopatologia , Doenças da Córnea/fisiopatologia , Pressão Intraocular/fisiologia , Espondilite Anquilosante/complicações , Tomografia de Coerência Óptica/métodos , Adulto , Córnea/patologia , Doenças da Córnea/diagnóstico , Doenças da Córnea/etiologia , Elasticidade , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Reprodutibilidade dos Testes , Adulto JovemRESUMO
Rosacea is a chronic cutaneous disorder which is known to cause inflammation and increased proteolytic activity on the ocular surface that might lead to corneal biomechanical alterations. The aim of this study is to evaluate the corneal biomechanical properties of ocular rosacea patients and compare the measurements with healthy individuals as measured with Reichert ocular response analyser (ORA). Besides full eye examination [best corrected visual acuity (BCVA), intraocular pressure (IOP) measured with Goldmann applanation tonometry (IOP-G)], central corneal thickness (CCT), and ORA [corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated IOP (IOPcc), Goldmann correlated IOP (IOPg)] measurements of 30 eyes of 15 ocular rosacea patients (study group) and 30 eyes of 15 healthy individuals (control group) were performed. For comparisons paired t test was used. Mean age of study group was 45.26 ± 11.65 (range 25 and 63) and control group was 45.00 ± 8.91 (range 26 and 58) years (p = 0.865). No significant difference in BCVA, CCT, IOP-G, IOPcc was detected among groups. However, IOPg, CH, and CRF in the study group were significantly lower than in the control group (p = 0.013, p = 0.013, p = 0.009, respectively). IOPg, CH, and CRF parameters of ocular rosacea patients were significantly lower than normal individuals. These differences and their probable clinical reflections that might effect making decisions in conditions such as glaucoma should be investigated in larger number of patients.
Assuntos
Córnea/patologia , Córnea/fisiopatologia , Pressão Intraocular/fisiologia , Rosácea/fisiopatologia , Adulto , Fenômenos Biomecânicos , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Tonometria Ocular , Acuidade Visual/fisiologiaRESUMO
The purpose of this study is to compare the corneal biomechanical properties in primary hyperparathyroid patients and healthy control subjects. The study consisted of 31 patients with primary hyperparathyroidism (study group) and 31 healthy subjects (control group). Corneal biomechanical properties, including corneal hysteresis (CH), corneal resistance factor (CRF), and intraocular pressure (IOP) were measured with an ocular response analyzer (ORA). IOP was also measured using Goldmann applanation tonometry (GAT), and central corneal thickness (CCT) was measured with an ultrasonic pachymeter. The differences in ORA parameters and CCT between study and control group participants were analyzed. The mean CH in study and control groups was 8.7 ± 1.9 mmHg (5.3-13.7 mmHg) and 9.8 ± 1.5 mmHg (7.7-14.3 mmHg), respectively (p = 0.018). The mean CRF was 9.5 ± 1.8 (5.5-13.7) in the study group compared with 9.8 ± 1.5 (6.2-12.8) in the control group. The difference for CRF was not statistically significant (p = 0.41). In study and control group, corneal-compensated IOP (IOPcc) values were 18.2 ± 4.2 and 16.9 ± 2.7 mmHg, respectively (p = 0.12). Mean IOP measurement values with GAT were 16.3 ± 3.4 mmHg for study group and 16.5 ± 2.7 mmHg for control group (p = 0.71). The mean differences of IOPcc and IOPGAT in the study group eyes were higher than that of control group eyes (1.9 vs. 0.4 mmHg). CCT was 536.5 ± 25.4 µm (490-593 µm) in study group eyes compared with 534.2 ± 31.4 µm (472-602 µm) in control eyes (p = 0.75). Hyperparathyroidism could be associated with a decrease of CH. The differences between IOPcc and IOPGAT in these patients were higher than normal subjects. Underestimation of IOP readings with GAT may be a consequence of the lower CH in patients with hyperparathyroididsm.
Assuntos
Córnea/fisiopatologia , Doenças da Córnea/fisiopatologia , Hiperparatireoidismo Primário/fisiopatologia , Pressão Intraocular/fisiologia , Córnea/patologia , Doenças da Córnea/diagnóstico , Doenças da Córnea/etiologia , Estudos Transversais , Elasticidade , Feminino , Humanos , Hiperparatireoidismo Primário/complicações , Masculino , Pessoa de Meia-Idade , Prognóstico , Acuidade VisualRESUMO
AIM: To determine the effect of drug-induced stress-relief tests on biomechanical properties of the ocular fibrous tunic in eyes with early, moderate, or advanced primary open-angle glaucoma (POAG). MATERIAL AND METHODS: A total of 202 eyes of 150 patients with POAG of different severity (early, moderate, or advanced) and 36 eyes of 30 healthy controls were examined. The mean patient age was 62±8.2 years. All groups were standardized by age, sex, and the range of corneal-compensated intraocular pressure (IOP) at baseline (21-30 mmHg). All patients underwent a standard ophthalmic examination, including visometry, biomicroscopy, gonioscopy, ophthalmoscopy, and Humphrey visual field assessment. Corneal hysteresis (CH), corneal resistance factor (CRF), CH-CRF difference, corneal-compensated IOP (IOPcc), and Goldmann-related IOP (IOPg) were measured with Ocular Response Analyzer (ORA, Reichert, USA). The axial eye length was measured on an ultrasonic A-scan (Ocuscan RxP, Alcon, USA) in the 10 MHz mode. RESULTS: CH and CRF variability analysis was conducted to assess changes in biomechanical properties of the fibrous tunic due to an IOP decrease and a tendency toward compensation. For the first time, the ratio between CH and CRF changes (ΔCH/ΔCRF) was used to evaluate biomechanical properties of the fibrous tunic. This ratio provides understanding of the significance of CH and CRF changes after reduction of IOP. In early glaucoma patients, it differed inconsiderably from the control group (p>0.05) and averaged 1.62±0.9. In moderate glaucoma, CH changes were more pronounced than those of CRF: ΔCH/ΔCRF - 2.03±2.41 (under conservative treatment) and 2.12±1.07 (without treatment). In advanced glaucoma an opposite pattern was observed: the CH/CRF ratio got closer to 1.0 largely due to CRF changes, while CH changes became much less pronounced (or even negative, in some cases): ΔCH/ΔCRF - 0.27±0.32 (under conservative treatment), 0.16±1.29 (without treatment). CONCLUSION: While the IOP decreased as a result of drug-induced stress-relief tests, CH and CRF changes differed between the groups depending on the stage of POAG. In early and moderate glaucoma, CH undergoes greater changes than CRF. In advanced glaucoma, CRF changes are more pronounced, and, hence, the ΔCH/ΔCRF ratio shifts reliably as glaucoma progresses. The ratio has also been shown to depend on the duration of the disease and on whether or not eye drops were prescribed.
Assuntos
Glaucoma de Ângulo Aberto/diagnóstico , Pressão Intraocular/efeitos dos fármacos , Sulfonamidas/administração & dosagem , Tiofenos/administração & dosagem , Timolol/administração & dosagem , Idoso , Anti-Hipertensivos/administração & dosagem , Fenômenos Biomecânicos , Técnicas de Diagnóstico Oftalmológico , Feminino , Glaucoma de Ângulo Aberto/fisiopatologia , Glaucoma de Ângulo Aberto/terapia , Gonioscopia/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Soluções Oftálmicas/administração & dosagem , Oftalmoscopia/métodos , Gravidade do Paciente , Tonometria Ocular/métodos , Testes de Campo Visual/métodosRESUMO
PURPOSE: The purpose was to investigate a possible association of corneal hysteresis (CH) and corneal resistance factor (CRF) with open-angle glaucoma and the severity of disease. METHODS: In this prospective cross-sectional study we recruited 86 open-angle glaucoma patients, 16 patients with ocular hypertension (OHT,) and 44 age-matched controls. Each participant had a complete glaucoma workup including measurements with the Ocular Response Analyzer and computerized perimetry with the Humphrey 30-2 SITA Standard program. Visual field damage was based on mean deviation (MD) and considered as early glaucomatous with a MD > - 6 dB, moderate glaucomatous between -6 and -12 dB and advanced glaucomatous < -12 dB. The association between ORA parameters, glaucoma, and disease severity was evaluated using univariate and multivariate linear regression analyses. RESULTS: There was a statistically significant correlation between the biomechanical parameters and intraocular pressure, central corneal thickness, axial length, and age. On average, glaucoma patients had the lowest adjusted CH (8.96 ± 1.43 mmHg) and CRF (9.07 ± 1.93 mmHg) values in comparison to OHT patients (CH: 10.2 ± 1.5 mmHg; CRF: 10.6 ± 2.1 mmHg) and controls (CH: 9.7 ± 1.4 mmHg; CRF: 10.2 ± 1.9 mmHg). This difference was statistically significant (CH: p = 0.003; CRF: p = 0.008). There was also a statistically significant difference in adjusted CH (p = 0.001) and CRF (p = 0.004) values between the controls and the visual field groups, with the lowest values being in the most advanced group. CONCLUSIONS: Before interpreting corneal biomechanical parameters, it seems important to adjust the measured data for their underlying influencing factors. Glaucoma patients with lower adjusted CH and CRF probably have more advanced disease and should, therefore, be treated more aggressively and monitored more carefully and frequently.